Electrical lead-through for pressure intensifier



April 12, 1966 R. HUDDLESTON ELECTRICAL LEAD-THROUGH FOR PRESSURE INTENSIFIER 2 Sheets-Sheet 1 Filed Jan. 8, 1965 INVENTOR.

Roy L. Huddlesfon ATTORNEY.

April 12, 1966 y L- Huddlesfon WQW ATTORNEY.

United States Patent 3,245,119 ELECTRICAL LEAD-THROUGH FOR PRESSURE INTENSIFIER Roy L. Huddleston, Knoxville, Tenn., assignor to the United States of America as represented by the United States Atomic Energy Commission Filed Jan. 8, 1965, Ser. No. 424,451 3 Claims. (Cl. 18-16) The present invention relates to pressure intensifying devices generally and more particularly to an improved electrical lead-through for the stationary piston of a piston-cylinder type high pressure intensifier.

Very high pressures have been utilized to effect material densification, phase transformations, and chemical changes. In many instances however, attainable pressures are insufficient to produce the desired result. In other cases the necessary pressure can be produced on very small samples only, making commercial application impractical. An additional factor which lessens the desirability of using high pressure alone, is the very high cost of pressure intensifiers which increases exponentially with pressure for any given working volume.

In practically all instances where densification or chemical reactions are accomplished through the application of high pressure, a considerably lower pressure would be sufficient if the temperature of the workpiece were raised. To accomplish such a rise in temperature, a resistance type heating element is normally used.. Such a heating arrangement requires electrical leads which must pass through one of the pistons or the cylinder wall in a pistoncylinder type pressure intensifier.

The passing of electrical leads from the outside of the pressure intensifier to its innermost high pressure cavity presents a difficult problem of preventing leakage of the Working fluid about the leads or a complete blow-out of the leads due to the lesser ability of the leads and their supporting packing to support large pressure-induced loads. When the electrical leads are used to supply resistance heaters within the interior of the pressure intensifier, the magnitude of the problem is increased due to the necessarily large cross section of the leads. A lesser problem exists where the leads are of the smaller size used for instrumentation. leads of both types are typically used where heat is applied to the high pressure cavity. The severity of the problem increases as the pressures developed within the intensifier increase.

It is, accordingly, a general object of the invention to provide improved means for admitting electrical leads to the interior of a pressure intensifier.

Other objects of the invention will become apparent from an examination of the following description of the invention and the appended drawings, wherein:

FIG. 1 is a vertical sectional view of a piston-cylinder type pressure intensifier incorporating the invention.

FIG. 2 is an enlarged isometric view, partly in section, of the stationary piston 2 shown in FIG. 1.

In accordance with the present invention, an improved means for admitting electrical leads to the interior of a piston-cylinder type high pressure intensifier is provided. A stationary piston having a centrally located bore is supported within the intensifier by a flat surfaced platen. Electrical wires lead from the interior of the intensifier through the central bore to insulated conductive members blocking the central bore at the piston exterior. From the conductive members blocking the bore, insulated flat conductive members pass between the stationary piston and the flat supporting platen to the exterior of the intensifier. The exterior surface of the stationary piston in contact with the platen, is made smaller than its interior surface so as to provide a greater pressure between the piston and platen than exists in the pressure 3,245,119 Patented Apr. 12, 1966 chamber within the intensifier. The higher pressure prevents leakage of the working fluid through the central bore of the piston and also prevents the flat conductive strips from being pushed outward.

To facilitate an understanding of the invention, reference is made to FIG. 1 of the accompanying drawings wherein a preferred embodiment of the invention is illustrated. Within one end of a multi-walled cylinder 1 of a piston-cylinder type pressure intensifier is fitted a stationary piston 2, tapered along its side to its exterior end 3. Fluid sealing between cylinder wall 4 and piston 2 is effected by O-rings 5. The open end 6 of cylinder 1 is closed by a flat platen 7 secured in a sealing position over the end of the cylinder by a plate member 8 bolted to a housing 9 encompassing cylinder 1. The slight taper (2 to 10 degrees) on the side wall of piston 2 adjacent to its exterior end 3, reduces the total surface area of the exterior end 3 of piston 2 where it contacts platen 7 so as to provide a slightly higher pressure at the piston-platen interface than that experienced within the pressure chamber 10 of the intensifier. This slightly higher pressure precludes outward flow of any fluid within the pressure chamber between piston 2 and platen 7.

Stationary piston member 2 contains a centrally located longitudinal bore 11 extending from its interior end 12 to its exterior end 3. The exterior end of bore 11 is plugged by four electrically conductive quadrantal wedges 13 electrically insulated from each other and the bore wall by epoxy mix 14 (Epon 828 with 20 parts per hundred of Z curing agent, manufactured by Shell Chemical Company). The epoxy, which fills bore 11 to the interior surface of piston 2, further acts to cement the wedges 13 in position. Under high pressure, the epoxy becomes semi-fluid but does not flow out of bore 11 due to the restraining force of the platen 7 and the high pressure which exists between piston 2 and platen 7. The epoxy does not flow upwardly into pressure chamber 10 due to the combined effects of its high viscosity and its adhesion to wedges 13 and the wall of bore 11. An antirotation dowel pin 17 is provided between platen 7 and piston 2.

Electrical continuity from pressure chamber 10 to the exterior of the intensifier is effected through wedges 13 by connecting a wire connector 15 to the interior end of each wedge, each wire connector leading to pressure chamber 10, and a flat, strong, electrically-insulated conductive strip 16 to the exterior end of each wedge. Conductive strip 16, which is made of a tempered Be-Cu alloy, lies flat between the exterior end 3 of piston 2 and platen 7 as depicted in FIGS. 1 and 2.

Other components illustrated in FIG. 1 include a movable stepped piston 19 comprising a larger diameter portion 20 and a reduced diameter portion 21 of substantially the same diameter as stationary piston 2.

FIG. 2 presents an enlarged isometric view of piston 2 showing the arrangement of wedges 13 within longitudinal bore 11, and two typical conductive strips 16. The converging tips of the four strips 16 fit closely together without contacting so as to substantially close the end of bore 11. The volume 18 between strips 16, including a small space between their converging tips, is filled with hard ceramic cement which also coats strips 16 to provide electrical insulation thereto. The ceramic cement is a mixture of Eastman 910 adhesive distributed by Armstrong Cork Company, Lancaster, Pennsylvania, and fine aluminum oxide powder. The positioned strips 16 are held by the large frictional force occasioned by their being disposed between piston 2 and platen 7 when piston 2 is being forced outward by pressure within cylinder 1.

The operation of piston-cylinder type pressure intensifiers is described in US. Patent No. 3,123,862, entitled Ultra-High Pressure Device, issued to common assignee.

The above description of one form of the invention was offered for illustrative purposes only, and should not be interpreted in a limiting sense. For example, the number of electrical leads passing through piston 2 may vary and may be more or less than the four leads illustrated in the embodiment. For this reason, it is intended that the invention be limited only by the claims appended hereto.

What is claimed is:

1. The improved means for passing electrical leads into the high pressure interior cavity of a piston-cylinder type pressure intensifier comprising: a stationary piston member sealably engaging the wall of said cavity, a flat surfaced platen retaining said piston within said cavity, said stationary piston member having a smaller surface area at its exterior end contacting said platen than on its interior end, said piston having a centrally located longitudinal bore extending from its interior end to its exterior end, at least one electrically insulated conductive member plugging said bore at the exterior end of said piston, a wire electrical conductor connected to the interior end of said conductive member and leading through said 1ongitudinal bore into said cavity, and a fiat electrically insulated conductor secured to the exterior end of said conductive member and passing between said stationary piston member and said platen to the exterior of said pressure intensifier.

2. The improved means for passing electrical leads into the high pressure interior cavity of a piston-cylinder type pressure intensifier comprising: a stationary piston member sealably engaging the wall of said cavity, a fiat surfaced platen retaining said piston within said cavity, said stationary piston having a smaller surface area at its exterior end contacting said platen than on its interior end adjacent said interior cavity, said piston having a centrally located longitudinal bore extending from its interior end to its exterior end, a plurality of electrically insulated wedge shaped conductors plugging said longitudinal bore at the exterior end of said piston, an electrically insulated 5,1. wire conductor connected to the interior end of each of said wedge conductors, said wire conductors leading from said Wedge shaped conductors through said longitudinal bore to said interior cavity, and a flat, electrically insulated conductor connected to the exterior end of each of said wedge shaped conductors, said fiat conductors passing between said stationary piston member and said platen to the exterior of said pressure intensifier.

3. The improved means for passing electrical leads into the cylindrical interior pressure cavity of a piston-cylinder type pressure intensifier comprising: a stationary piston member having substantially the same diameter as said cylindrical cavity, said stationary piston sealably engaging the wall of said cavity, a flat surfaced platen retaining said piston within said cavity, said stationary piston being tapered at its exterior end to a diameter which is smaller than the diameter of said cylindrical interior cavity, said stationary piston member having a centrally located cylindrical bore extending therethrough, a plurality of electrical conductors in the form of longitudinal segments of a cylinder substantially filling the exterior end of said bore, electrically insulated wire conductors connected to the interior end of each of said wedge shaped electrical conductors, said wire conductors leading from the interior end of each of said Wedge shaped conductors through said longitudinal bore to said interior cavity, flat conductors leading from the exterior end of each of said wedge shaped conductors between said stationary piston and platen to the exterior of said pressure intensifier, and an epoxy mix disposed about and between said wedge shaped conductors to electrically insulate and secure them within said longitudinal bore, and ceramic cement disposed between said stationary piston and said platen, said ceramic cement providing electrical insulation to said flat conductors passing between said piston and said platen.

No references cited.

LARAMIE E. ASKIN, Primary Examiner. 

1. THE IMPROVED MEANS FOR PASSING ELECTRICAL LEADS INTO THE HIGH PRESSURE INTERIOR CAVITY OF A PISTON-CYLINDER TYPE PRESSURE INTENSIFIER COMPRISING: A STATIONARY PISTON MEMBER SEALABLY ENGAGING THE WALL OF SAID CAVITY, A FLAT SURFACED PLATEN RETAINING SAID PISTON WITHIN SAID CAVITY, SAID STATIONARY PISTON MEMBER HAVING A SMALLER SURFACE AREA AT ITS EXTERIOR END CONTACTING SAID PLATEN THAN ON ITS INTERIOR END, SAID PISTON HAVING A CENTRALLY LOCATED LONGITUDINAL BORE EXTENDING FROM ITS INTERIOR END TO ITS EXTERIOR END, AT LEAST ONE ELECTRICALLY INSULATED CONDUCTIVE MEMBER PLUGGING SAID BORE AT THE EXTERIOR END OF SAID PISTON, A WIRE ELECTRICAL CONDUCTOR CONNECTED TO THE INTERIOR END OF SAID CONDUCTIVE MEMBER AND LEADING THROUGH SAID LONGITUDINAL BORE INTO SAID CAVITY, AND A FLAT ELECTRICALLY INSULATED CONDUCTOR SECURED TO THE EXTERIOR END OF SAID CONDUCTIVE MEMBER AND PASSING BETWEEN SAID STATIONARY PISTON MEMBER AND SAID PLATEN TO THE EXTERIOR OF SAID PRESSURE INTENSIFIER. 